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Re: Problems connectivity GE on Foundry BigIron to Cisco 2950T
- From: Sam Stickland
- Date: Sun Jan 15 19:51:56 2006
Wikipedia reveals all. http://en.wikipedia.org/wiki/Crossover_cable
Turns out that for 1000Base-T crossovers pairs 2 and 3, and 1 and 4 have
to swapped. Standard TIA-568B to TIA-568A over swaps 2 and 3.
Auto MDI/MDI-X is optional in the 1000Base-T spec so the way forward is to
try a straight cable and if that fails I'll have to make up a 1000Base-T
Thanks for all the help people,
On Mon, 16 Jan 2006, Sam Stickland wrote:
On Mon, 16 Jan 2006, Mark Smith wrote:
On Sun, 15 Jan 2006 23:50:07 +0000 (GMT Standard Time)
Sam Stickland <email@example.com> wrote:
The cabling arrangement is:
Foundry -- Straight -- Patch -- Underfloor -- Patch -- Crossover -- Cisco
GBIC Cable Panel Straight Panel Cable
If I replace the final crossover cable with a straight,
Just do that ^^^ and give it a try.
If that fails I might have to dig out a non-passive 1000SX to 1000-BaseT
media convertor that's on one of the other sites and give that a try.
Btw, several people have suggested "speed nonegotiate" on the cisco speed.
This command is only supported on GBIC slots on cisco, not on fixed
1000Base-T interfaces (at least not a Sup720/WS-X6748-GE-TX).
I also found this reference about the clock signals in use on 1000Base-T:
1000BASE-T is based on synchronous transmission to facilitate the cancelation
of Echo/NEXT/FEXT interferences at the receivers. To achieve synchronous
transmission between the two PHYs at the ends of a link, a master-slave
clocking relationship is established by the PHYs. The master-slave
relationship between two stations sharing a link segment is established
during auto-negotiation. The master PHY uses an external clock to determine
the timing of transmitter and receiver operations. This master clock is also
provided to the other stations in the network. The slave PHY recovers the
clock from the received signal and uses it to determine the timing of
transmitter operations. In a typical network, the PHY at the repeater will
become the master and the PHY at the data terminal equipment (DTE) will
become the slave."
So it would appear that auto-negotiation is a requirement in 1000Base-T.